FLS2023 - Classification: C - Compact Light Sources

Paper	Title	Page
MO1L1	EuPRAXIA: The First FEL User Facility Driven by a Plasma Accelerator
	R.W. Aßmann DESY, Hamburg, Germany
	Funding: Supported by the European Unions Horizon Europe research and innovation programme under grant agreement No. 101079773 and 101073480, the Swiss government and the UKRI guarantee funds. The European Plasma Accelerator with eXcellence In Applications (EuPRAXIA) infrastructure* was proposed in 2014 and started its design phase in 2015 with an EU funded Design Study. By the end of 2019 the World‘s first conceptual design report (CDR) for a plasma-based user facility was completed. The EuPRAXIA CDR describes the design of a compact and innovative research infrastructure that delivers ultra-short pulses of up to 5 GeV electrons, positrons, X-rays, FEL light and laser pulses to users from various fields. The project received government support from various European contries and was placed on the ESFRI roadmap of high priority European research infrastructures at end of 2021. The EuPRAXIA headquarters and one of the two construction sites is located at Frascati, Rome, in Italy. The second site will be decided among candidates in Czech Republic, Italy, Spain and UK. Presently several projects, supported by national and EU funds, are ongoing towards the implementation of this new research infrastructure. The talk will present the concept, user cases, the technical status, including successful FEL lasing, the potential and challenges for EuPRAXIA. https://www.eupraxia-facility.org/ R.W. Assmann et al., Eur. Phys. J. Special Topics 229, 3675-4284 (2020). * R. Pompili et al. Nature 605 (2022) 7911, 659-662.
	Slides MO1L1 [21.766 MB]
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MO1L2	Free-electron Light Interactions in Nanophotonics
	C. Roques-Carmes Stanford University, Stanford, California, USA
	Nanophotonics has become over the past decades a paramount technology, enabling, among other things, the design of novel light sources, detectors, and devices controlling the polarization, spectral, and angular distribution of light. A landmark of nanophotonics is the design of nanostructured materials (metasurfaces, photonic crystals, nanoresonators, etc.) to tailor the interaction of light with matter, either by shaping light propagation at the nanoscale, or by controlling emission from atoms and molecules. In this talk, I will show how one can enhance and tailor radiation from high-energy particles, such as free electrons and x-rays with engineered nanophotonics structures. I will present a framework to model, tailor, enhance, and even optimize radiation from free electrons and other high-energy particles interacting with nanophotonic structures. I will then describe the building of a featured experimental setup to record spectrally-resolved light emission from free electrons interacting with nanophotonic structures. I will focus on the example of nanophotonic flatbands in photonic crystals, which can be used to enhance free-electron radiation and acceleration by orders of magnitude by overcoming phase-matching limitations. I will utilize our methods to demonstrate nanophotonic enhancement of coherent cathodoluminescence from free electrons and discuss new frontiers in the quantum optics of free electrons
	Slides MO1L2 [13.704 MB]
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MO4C1	Ultra-bright Coherent Undulator Radiation Driven by Dielectric Laser Accelerator
	Y.-C. Huang NTHU, Hsinchu, Taiwan
	Funding: National Science and Technology Council under Contract MOST 111-2221-E-007-001 A dielectric laser accelerator, operating at optical frequencies and GHz pulse rate, is expected to produce attosecond electron bunches with a moderate beam current at high energy. For relativistic electrons, the attosecond bunch has a spatial length of a few nanometers, which is well suited for generating high-brightness superradiance in the VUV, EUV, and X-ray spectra. Our study shows that the brilliance of coherent undulator radiation driven by a short-bunch beam with 1~10 fC bunch charge from a dielectric laser accelerator is comparable to or higher than that of a synchrotron in the 0.1~3 keV photon energy range, even though the beam power of the dielectric laser accelerator is about a million times lower than that of a synchrotron. When the brilliance under comparison is normalized to the electron beam power, the proposed coherent undulator radiation source becomes the brightest source on earth across the whole VUV, EUV, and soft x-ray spectrum.
	Slides MO4C1 [3.054 MB]
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MO4C2	Development of a Compact Light Source using a Two-beam-acceleration Technique	42
	P. Piot, E.A. Frame, X. Lu Northern Illinois University, DeKalb, Illinois, USA G. Chen, C.-J. Jing, X. Lu, J.G. Power ANL, Lemont, Illinois, USA C.-J. Jing, S.V. Kuzikov Euclid Beamlabs, Bolingbrook, USA
	Funding: This work is supported by the U.S. DOE, under award No. DE-AC02-06CH11357 with ANL. This work is partially supported by Laboratory Directed Research and Development (LDRD) funding at ANL. The recent demonstration of sub-GV/m accelerating fields at X-band frequencies* offers an alternative pathway to designing a compact light source. The high fields were enabled by powering the accelerating structures using short (<10 ns) X-band RF pulses produced via a two-beam-accelerator (TBA) scheme. In this contribution, we present a conceptual design to scale the concept to a ~0.5 GeV accelerator. We present the optimization of the photoinjector and preliminary beam-dynamics modeling of the accelerator. Finally, we will discuss ongoing and planned experiments toward developing an integrated proof-of-principle experiment at Argonne National Laboratory combining the 0.5 GeV linac with a free-electron laser. * W.H. Tan, et al. DOI: 10.1103/PhysRevAccelBeams.25.083402 (2022).
	Slides MO4C2 [2.690 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO4C2
About •	Received ※ 31 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
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MO4C3	Generation of GeV Photon Energy at European X-Ray Free Electron Laser
	I. Drebot INFN-Milano, Milano, Italy N.S. Mirian DESY, Hamburg, Germany F. Zimmermann CERN, Meyrin, Switzerland
	Intense high-energy photon beams (>1 GeV) with multiple outstanding characteristics, such as energy tunability, good directivity, quasi-monochromaticity, etc., offer numerous novel applications in nuclear physics, high-energy physics, and non-destructive material analysis. Potential applications of the high photon energy include protein crystallography, along with searches for Dark Photons and Axion-like Particles. European X-ray free electron laser based on superconductor linear accelerator is able to generate short high current electron bunches at megahertz intra-train repetition rate in the range of 17.5 GeV energy. We employ its capabilities and show the potential of this facility in the generation of GeV photon energy. We employ laser Compton scattering at the spreader of the south branch FEL line and simulate the generation of GeV photon energy
	Slides MO4C3 [5.299 MB]
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TU1C1	An Efficient Optimisation of a Burst Mode-Operated Fabry-Perot Cavity for Compton Light Sources	46
	V. Mușat, E. Granados, A. Latina CERN, Meyrin, Switzerland E. Cormier CELIA, Talence, France G. Santarelli ILE, Palaiseau Cedex, France
	The burst mode operation of a Fabry-Perot cavity (FPC) allows for the generation of a high-intensity photon beam in inverse Compton scattering (ICS) sources. The geometry and burst mode parameters of the FPC can be optimised to maximise the scattered photon flux. A novel optimisation method is presented, significantly improving processing speed and accuracy. The FPC’s dimensions, mirror requirements, and effective energy can be obtained from the electron beam parameters at the interaction point. A multi-objective optimization algorithm was used to derive the geometrical parameters of the FPC; this brought orders of magnitude increase in computation speed if compared to the nominal Monte Carlo-based approaches. The burst mode parameters of the FPC were obtained by maximizing the effective energy of the laser pulse in the FPC. The impact of optical losses and thermal lensing on the FPC parameters is addressed. Preliminary parameters of an ICS source implementing this novel optimisation are presented. The source could reach high-performance photon beams for high-energy applications.
	Slides TU1C1 [1.776 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C1
About •	Received ※ 22 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU1C2	Evolution of the Inverse Compton Scattering X-ray Source of the ELSA Accelerator	50
	A. Pires, R. Rosch, J. Touguet CEA, Arpajon, France N. Delerue Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France V. Le Flanchec CEA/DAM/DIF, Arpajon, France
	The Inverse Compton Scattering (ICS) X-ray source of ELSA accelerator at CEA-DAM, presents an efficient approach for generating X-rays with a compact linac. The source consists of a 30 MeV, 15 ps rms, up to 3 nC electron beam; and a table-top Nd:YAG laser. X-rays are produced in the 10-80 keV range, higher X-ray energies achieved with frequency doubling of the laser. The yield is increased by a factor of 8 thanks to an optical mirror system developed at CEA, folding the laser beam path and accumulating successive laser pulses. We present a new version of the device, with improvement of mechanical constraints management, adjunction of motorized mirrors, and a new imaging system. A Chirped Pulse Amplification (CPA) system was also designed, enabling higher amplification levels without exceeding laser damage threshold. The uniqueness of this CPA system lies in its use of a short wavelength bandwidth, ±250 pm after Self-Phase Modulation (SPM) broadening, and a line density of 1850 lines/mm for the gratings of the compressor. The pulse is stretched with a chirped fiber Bragg grating (CFBG) before amplification in Nd:YAG amplifiers, and compressed by a double pass grating compressor.
	Slides TU1C2 [7.085 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C2
About •	Received ※ 25 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU1C3	A Compton Light Source Based on Counter Propagating Direct Laser Acceleration Channels
	T. Meir, I. Cohen, L. Perelmutter, I. Pomerantz Tel Aviv University, Tel-Aviv, Israel A.V. Arefiev, K. Tangtartharakul UCSD, La Jolla, California, USA T. Cohen Soreq NRC, Yavne, Israel
	For the past two decades, intense lasers have supported new schemes for generating high-energy particle beams in university-scale laboratories. With the direct laser acceleration (DLA) method, the leading part of the laser pulse ionizes the target material and forms a positively charged ion plasma channel into which electrons are injected and accelerated. A striking feature of DLA is the extremely high conversion efficiency from laser energy to MeV electrons, with reported values as high as 23%, which makes this mechanism ideal for generating large numbers of photo-nuclear reactions. DLA is well understood and reproduced in numeric simulations. However, the electron energies obtained with the highest laser intensities available nowadays, fail to meet numerical predictions. In an experimental campaign, followed by a numerical investigation, we revealed that at these higher laser intensities, the leading edge of the laser pulse may deplete the target material of its ionization electrons prematurely. We demonstrated that for efficient DLA to prevail, a target material of sufficiently high atomic number is required to maintain the injection of ionization electrons at the peak intensity of the pulse when the DLA channel is already formed. I will present a numerical study on employing this new understanding for realizing a high brightness Compton light source in two counter-propagating DLA channels. Our 3D particle-in-cell results indicate small cone-angle photon emission in the multi 10s of keV spectral range, with few-fs duration and micron-scale source size.
	Slides TU1C3 [6.684 MB]
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TU1C4	The CXFEL Project at Arizona State University	54
	W.S. Graves ASU, Tempe, USA
	Funding: This work supported by National Science Foundation awards 2153503, 1935994, and 1632780. The CXFEL Project encompasses the Compact X-ray Light Source (CXLS) that is now commissioning in the hard x-ray energy range 4-20 keV, and the Compact X-ray Free-Electron Laser (CXFEL) designed to lase in the soft x-ray range 300 ¿ 2500 eV. CXFEL has recently completed a 3-year design phase and just received NSF funding for construction over the next 5 years. These instruments are housed in separate purpose-built laboratories and rely on inverse Compton scattering of bright electron beams on powerful lasers to produce femtosecond pulses of x-rays from very compact linacs approximately 1 m in length. Both instruments use recently developed X-band distributed-coupling, room-temperature, standing-wave linacs and photoinjectors operating at 1 kHz repetition rates and 9300 MHz RF frequency. They rely on recently developed Yb-based lasers operating at high peak and average power to produce fs pulses of 1030 nm light at 1 kHz repetition rate with pulse energy up to 400 mJ. We present the current commissioning performance and status of CXLS. We also review the design and initial construction activities of the large collaborative effort to develop the fully coherent CXFEL.
	Slides TU1C4 [7.974 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C4
About •	Received ※ 30 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023
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TU4P31	A Recursive Model for Laser-Electron-Radiation Interaction in Insertion Section of SSMB Storage Ring Based on Transverse-Longitudinal Coupling Scheme	147
	C.-Y. Tsai HUST, Wuhan, People’s Republic of China X.J. Deng TUB, Beijing, People’s Republic of China
	Funding: This work is supported by the Fundamental Research Funds for the Central Universities (HUST) under Project No. 2021GCRC006 and National Natural Science Foundation of China under project No. 12275094. Recently a mechanism of the steady-state microbunching (SSMB) in a storage ring has been proposed and investigated. The SSMB aims to maintain the same excellent high repetition rate, close to continuous-wave operation, as the storage ring. Moreover, replacing the conventional RF cavity with a laser modulator for longitudinal focusing, the individual electron bunches can be microbunched in a steady state. The microbunched electron bunch train, with individual bunch length comparable to or shorter than the radiation wavelength, can not only produce coherent powerful synchrotron radiations but may also be subject to FEL-like collective instabilities. Our previous analysis was based on the wake-impedance model. In this paper, we have developed a recursive model for the laser modulator in the SSMB storage ring. In particular, the transverse-longitudinal coupling scheme is assumed. Equipped with the above matrix formalism, we can construct a recursive model to account for turn-by-turn evolution, including single-particle and second moments. It is possible to obtain a simplified analytical expression to identify the stability regime or tolerance range for non-perfect cancellation. C.-Y. Tsai, PRAB 25, 064401 (2022). C.-Y. Tsai, NIMA 1042 (2022) 167454. **X.J. Deng et al., NIMA 1019 (2021) 165859.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P31
About •	Received ※ 23 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P33	An Inverse-Compton Scattering Simulation Module for RF-Track	151
	A. Latina, V. Mușat CERN, Meyrin, Switzerland
	A simulation module implementing Inverse-Compton scattering (ICS) was added to the tracking code RF-Track. The module consists of a special beamline element that simulates the interaction between the tracked beam and a laser, making RF-Track capable of simulating a complete ICS source in one go, from the electron source to the photons. The description of the laser allows the user to thoroughly quality the laser in terms of wavelength, pulse energy, pulse length, incoming direction, M2 parameter, aspect ratio, polarisation and whether the laser profile should be Gaussian or uniform. Furthermore, as the code implements fully generic expressions, the scattering between photons and different particles than electrons can be simulated. A benchmark against CAIN showed excellent agreement and that RF-Track outperforms CAIN in terms of computational speed by orders of magnitude.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P33
About •	Received ※ 22 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TU4P34	Recent Developments of the cSTART Project	155
	M. Schwarz, A. Bernhard, E. Bründermann, D. El Khechen, B. Härer, A. Malygin, A.-S. Müller, M.J. Nasse, G. Niehues, A.I. Papash, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski, C. Widmann KIT, Karlsruhe, Germany
	The combination of a compact storage ring and a laser-plasma accelerator (LPA) can serve as the basis for future compact light sources. One challenge is the large momentum spread (~ 2%) of the electron beams delivered by the LPA. To overcome this challenge, a very large acceptance compact storage ring (VLA-cSR) was designed as part of the compact STorage ring for Accelerator Research and Technology (cSTART) project. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for the VLA-cSR to benchmark and emulate LPA-like beams. In a second stage, a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and the Helmholtz Institute Jena (HIJ). The small facility footprint, the large-momentum spread bunches with charges from 1 pC to 1 nC and lengths from few fs to few ps pose challenges for the lattice design, RF system and beam diagnostics. This contribution summarizes the latest results on these challenges.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P34
About •	Received ※ 21 August 2023 — Revised ※ 22 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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WE2C1	Population Inversion X-ray Laser Oscillator at LCLS and LCLS-II
	A. Halavanau, A. Aquila, U. Bergmann, C. Pellegrini SLAC, Menlo Park, California, USA A.I. Benediktovitch DESY, Hamburg, Germany N. Majernik UCLA, Los Angeles, California, USA N. Rohringer Max Planck Institute for the Physics of Complex Systems, Dresden, Germany N.B. Welke UW-Madison/PD, Madison, Wisconsin, USA
	The advancement of X-ray Free Electron Lasers (XFELs) has created revolutionary new research opportunities, owing to their high peak and average power, transverse coherence, and short pulse duration. Despite their remarkable capabilities, XFEL pulses lack longitudinal coherence and are not transform-limited, which limits their utilization, e.g. in quantum optics and precision interferometry. We explore the development of coherent, transform-limited pulses through alternative strategies, namely, X-ray lasers based on population inversion. We propose a novel approach relying on the principle of stimulated emission in the hard X-ray regime, using the XFEL as a pump. We will specifically discuss the case of the X-ray Laser Oscillator (XLO) at the LCLS copper linac and the planed LCLS-II-HE. Our recent work has shown the feasibility and performance characteristics of these systems, which can operate over a broad wavelength range from 5 to 12 keV. Future applications at LCLS-II-HE might allow for transform-limited XLO pulses with repetition rates up to tens of kHz. We show that XLO is experimentally feasible and discuss its projected performance and photon pulse properties operating at the Copper K-alpha1 line. Finally, we discuss possible first experiments with XLO.
	Slides WE2C1 [2.756 MB]
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WE2C2	Harmonic Generation from keV-electron-excited Nano-grating
	Y.-C. Huang NTHU, Hsinchu, Taiwan
	Funding: MOST 111-2221-E-007-001, Taiwan There has been a recent interest in using free electrons to interact with photonic structures and generate light. The envisaged dielectric accelerator on a chip is a low-current electron source driven by a laser. The generated electron beam contains a few electrons in each optical cycle repeating at the driver laser frequency. We perform a feasibility study in this paper on the harmonic generation of a periodic array of single electrons with keV energy atop a dielectric grating waveguide. The device is a 31 um long silicon grating on top of a glass substrate, having a 400 nm thickness and 310-nm period. The structure is designed to have a Bragg resonance at 1.5 um in wavelength or 0.2 PHz in frequency for the radiation mode. We use the simulation code CST to study the radiation from a periodic array of 25 electrons. The electrons have 50 keV energy, injected one by one at 0.1 PHz at 100 nm above the grating. The transit time of the 50 keV electrons over the 31 um long silicon grating is 0.25 ps. Cherenkov radiation is guided in the silicon waveguide layer. Smith-Purcell (SP) radiation is generated in the vacuum region above the grating. We show in simulation a ring-down of the generated coherent radiations from both ends of the grating waveguide, indicating that a grating waveguide is a good Bragg resonator. The field pattern in the waveguide region satisfies the Bragg condition, i.e. structure periodicity = half of the longitudinal wavelength. The Fourier transform of the generated radiation wave has a narrow radiation spectrum at 0.2 PHz. A discrete spectrum of SP radiation mediated by the waveguide modes is also observed from simulation in the vacuum space above the grating waveguide. This study shows the feasibility of generating harmonic radiation from a nano-photonic structure driven by keV periodic electrons.
	Slides WE2C2 [3.982 MB]
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TH2C1	The COXINEL Seeded Free Electron Laser Driven by the Laser Plasma Accelerator at HZDR	232
	M.-E. Couprie, T. André, A. Berlioux, P. Berteaud, F. Blache, F. Bouvet, F. Briquez, Y. Dietrich, J.P. Duval, M. El Ajjouri, C. Herbeaux, N. Hubert, C.A. Kitégi, M. Labat, S. Lê, B. Leluan, A. Loulergue, F. Marteau, M.-H. Nguyen, D. Oumbarek Espinos, D. Pereira, J.P. Ricaud, P. Rommeluère, M. Sebdaoui, K. Tavakoli, M. Valléau, M.V. Vandenberghe, J. Vétéran, C. de Oliveira SOLEIL, Gif-sur-Yvette, France I.A. Andriyash, J. Gautier, J.-P. Goddet, O.S. Kononenko, G. Lambert, J.P. Rousseau, A. Tafzi, C. Thaury LOA, Palaiseau, France S. Bock, Y.Y. Chang, A.D. Debus, C. Eisenmann, R. Gebhardt, A. Ghaith, S. Grams, U. Helbig, A. Irman, M. Kuntzsch, R.G. Pausch, T. Püschel, S. Schöbel, U. Schramm, K. Steiniger, P. Ufer HZDR, Dresden, Germany M. LaBerge The University of Texas at Austin, Austin, Texas, USA V. Malka Weizmann Institute of Science, Physics, Rehovot, Israel E. Roussel PhLAM/CERLA, Villeneuve d’Ascq, France
	Laser Plasma Accelerators know a tremendous development these recent years. Being able to reach up to ~100 GV/m, they open new perspectives for compact accelerators. Their performance can be qualified by a Free Electron Laser Application. We report here on the COXINEL seeded Free Electron Laser in the UV using the using high-quality electron beam generated by the 150 TW DRACO laser. The COXINEL line developed at Synchrotron SOLEIL (France) is first introduced. First electron beam transport and undulator radiation observation using electrons from the Laser Plasma Accelerator developed at Laboratoire d’Optique Appliquée (France) are described. Then, we present the first COXINEL results driven by the DRACO laser high performance plasma accelerator after its move to Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Germany): proper electron beam transport, undulator seed and undulator radiation temporal, spectral and spatial overlaps, allowing the seeded Free Electron Laser to be observed in the UV. Good agreement is found between measurements and simulations.
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH2C1
About •	Received ※ 22 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023
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TH2C2	Development of Laser-Driven Plasma Accelerator Undulator Radiation Source at ELI-Beamlines	237
	A.Y. Molodozhentsev Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic J.T. Green, P. Zimmermann ELI-BEAMS, Prague, Czech Republic A. Jancarek, S.M. Maity, A. Mondal, S.N. Niekrasz, E. Vishnyakov ELI ERIC, Dolni Brezany, Czech Republic
	Over the last decade, the mechanism of the laser-plasma acceleration of electrons was studied intensively by many experimental teams aiming to achieve high-energy, high-quality electron beams required to generate high-brilliance incoherent and, as the next step, coherent undulator photon radiation for wide-range applications. The laser-driven plasma accelerator based compact undulator radiation source is currently under commissioning at ELI-Beamlines (Institute of Physics CAS, Czech Republic) in the frame of the LUIS project, which aims to deliver stable and reliable incoherent photon beam with a wavelength around 5 nm to an user-station. As the result of this project, the electron beam parameters should be improved to generate the coherent photon radiation reaching the saturation of the photon pulse energy in a single-unit dedicated undulator (LPA-based FEL). An overview of the current status of the LUIS project will be presented, including the high-power high-repetition rate laser, acceleration of the electron beam in the plasma channel, the electron and photon beam-lines with relevant diagnostics. Challenges and future development beyond the LUIS project also being discussed.
	Slides TH2C2 [3.474 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH2C2
About •	Received ※ 23 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023
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TH2C3	A Novel X-ray Free-electron Laser Scheme Based on Cascaded Laser Wakefield Accelerators
	H.Y. Xiao, J.F. Hua, F. Li, W. Lu TUB, Beijing, People’s Republic of China
	Laser wakefield accelerators (LWFA) present great potential to drive a free-electron laser (FEL) in a compact footprint because of the extremely high accelerating gradient. However, there are still many obstacles to overcome before the LWFA-driven FEL device can truly achieve exponential amplification and saturated output. These problems include how to resolve the phase slippage effect caused by the fs-level length of LWFA beams, and how to stably generate high-quality beams and preserve the quality during the transport. In this presentation, a novel scheme of X-ray FEL based on cascaded LWFAs is proposed aiming at addressing the above issues. High-quality electron beams with stable central energy and relatively long beam length can be generated using staged LWFAs. With a dedicated beamline design, the longitudinal phase space, beam length and inter-stage coupling are optimized, and start-to-end simulations show that such beams can drive the XFEL to saturation. In addition, the proposed scheme also possesses the capability to adjust FEL radiation bandwidth through precise longitudinal phase space steering. Our scheme provides a highly viable new route to realize LWFA-driven compact XFEL devices.
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FR1M3	Summary Report of Working Group C: Compact Light Sources
	Y.-C. Huang NTHU, Hsinchu, Taiwan P. Piot Northern Illinois University, DeKalb, Illinois, USA
	The paper highlights the key points arising from four insightful and instructive working group sessions.
	Slides FR1M3 [8.910 MB]
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Paper

Title

Page

MO1L1

EuPRAXIA: The First FEL User Facility Driven by a Plasma Accelerator

R.W. Aßmann
DESY, Hamburg, Germany

Funding: Supported by the European Unions Horizon Europe research and innovation programme under grant agreement No. 101079773 and 101073480, the Swiss government and the UKRI guarantee funds.
The European Plasma Accelerator with eXcellence In Applications (EuPRAXIA) infrastructure* was proposed in 2014 and started its design phase in 2015 with an EU funded Design Study. By the end of 2019 the World‘s first conceptual design report (CDR) for a plasma-based user facility was completed. The EuPRAXIA CDR** describes the design of a compact and innovative research infrastructure that delivers ultra-short pulses of up to 5 GeV electrons, positrons, X-rays, FEL light and laser pulses to users from various fields. The project received government support from various European contries and was placed on the ESFRI roadmap of high priority European research infrastructures at end of 2021. The EuPRAXIA headquarters and one of the two construction sites is located at Frascati, Rome, in Italy. The second site will be decided among candidates in Czech Republic, Italy, Spain and UK. Presently several projects, supported by national and EU funds, are ongoing towards the implementation of this new research infrastructure. The talk will present the concept, user cases, the technical status, including successful FEL lasing***, the potential and challenges for EuPRAXIA.
* https://www.eupraxia-facility.org/
** R.W. Assmann et al., Eur. Phys. J. Special Topics 229, 3675-4284 (2020).
*** R. Pompili et al. Nature 605 (2022) 7911, 659-662.

Slides MO1L1 [21.766 MB]

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MO1L2

Free-electron Light Interactions in Nanophotonics

C. Roques-Carmes
Stanford University, Stanford, California, USA

Nanophotonics has become over the past decades a paramount technology, enabling, among other things, the design of novel light sources, detectors, and devices controlling the polarization, spectral, and angular distribution of light. A landmark of nanophotonics is the design of nanostructured materials (metasurfaces, photonic crystals, nanoresonators, etc.) to tailor the interaction of light with matter, either by shaping light propagation at the nanoscale, or by controlling emission from atoms and molecules. In this talk, I will show how one can enhance and tailor radiation from high-energy particles, such as free electrons and x-rays with engineered nanophotonics structures. I will present a framework to model, tailor, enhance, and even optimize radiation from free electrons and other high-energy particles interacting with nanophotonic structures. I will then describe the building of a featured experimental setup to record spectrally-resolved light emission from free electrons interacting with nanophotonic structures. I will focus on the example of nanophotonic flatbands in photonic crystals, which can be used to enhance free-electron radiation and acceleration by orders of magnitude by overcoming phase-matching limitations. I will utilize our methods to demonstrate nanophotonic enhancement of coherent cathodoluminescence from free electrons and discuss new frontiers in the quantum optics of free electrons

Slides MO1L2 [13.704 MB]

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MO4C1

Ultra-bright Coherent Undulator Radiation Driven by Dielectric Laser Accelerator

Y.-C. Huang
NTHU, Hsinchu, Taiwan

Funding: National Science and Technology Council under Contract MOST 111-2221-E-007-001
A dielectric laser accelerator, operating at optical frequencies and GHz pulse rate, is expected to produce attosecond electron bunches with a moderate beam current at high energy. For relativistic electrons, the attosecond bunch has a spatial length of a few nanometers, which is well suited for generating high-brightness superradiance in the VUV, EUV, and X-ray spectra. Our study shows that the brilliance of coherent undulator radiation driven by a short-bunch beam with 1~10 fC bunch charge from a dielectric laser accelerator is comparable to or higher than that of a synchrotron in the 0.1~3 keV photon energy range, even though the beam power of the dielectric laser accelerator is about a million times lower than that of a synchrotron. When the brilliance under comparison is normalized to the electron beam power, the proposed coherent undulator radiation source becomes the brightest source on earth across the whole VUV, EUV, and soft x-ray spectrum.

Slides MO4C1 [3.054 MB]

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MO4C2

Development of a Compact Light Source using a Two-beam-acceleration Technique

42

P. Piot, E.A. Frame, X. Lu
Northern Illinois University, DeKalb, Illinois, USA
G. Chen, C.-J. Jing, X. Lu, J.G. Power
ANL, Lemont, Illinois, USA
C.-J. Jing, S.V. Kuzikov
Euclid Beamlabs, Bolingbrook, USA

Funding: This work is supported by the U.S. DOE, under award No. DE-AC02-06CH11357 with ANL. This work is partially supported by Laboratory Directed Research and Development (LDRD) funding at ANL.
The recent demonstration of sub-GV/m accelerating fields at X-band frequencies* offers an alternative pathway to designing a compact light source. The high fields were enabled by powering the accelerating structures using short (<10 ns) X-band RF pulses produced via a two-beam-accelerator (TBA) scheme. In this contribution, we present a conceptual design to scale the concept to a ~0.5 GeV accelerator. We present the optimization of the photoinjector and preliminary beam-dynamics modeling of the accelerator. Finally, we will discuss ongoing and planned experiments toward developing an integrated proof-of-principle experiment at Argonne National Laboratory combining the 0.5 GeV linac with a free-electron laser.
* W.H. Tan, et al. DOI: 10.1103/PhysRevAccelBeams.25.083402 (2022).

Slides MO4C2 [2.690 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-MO4C2

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Received ※ 31 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

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MO4C3

Generation of GeV Photon Energy at European X-Ray Free Electron Laser

I. Drebot
INFN-Milano, Milano, Italy
N.S. Mirian
DESY, Hamburg, Germany
F. Zimmermann
CERN, Meyrin, Switzerland

Intense high-energy photon beams (>1 GeV) with multiple outstanding characteristics, such as energy tunability, good directivity, quasi-monochromaticity, etc., offer numerous novel applications in nuclear physics, high-energy physics, and non-destructive material analysis. Potential applications of the high photon energy include protein crystallography, along with searches for Dark Photons and Axion-like Particles. European X-ray free electron laser based on superconductor linear accelerator is able to generate short high current electron bunches at megahertz intra-train repetition rate in the range of 17.5 GeV energy. We employ its capabilities and show the potential of this facility in the generation of GeV photon energy. We employ laser Compton scattering at the spreader of the south branch FEL line and simulate the generation of GeV photon energy

Slides MO4C3 [5.299 MB]

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TU1C1

An Efficient Optimisation of a Burst Mode-Operated Fabry-Perot Cavity for Compton Light Sources

46

V. Mușat, E. Granados, A. Latina
CERN, Meyrin, Switzerland
E. Cormier
CELIA, Talence, France
G. Santarelli
ILE, Palaiseau Cedex, France

The burst mode operation of a Fabry-Perot cavity (FPC) allows for the generation of a high-intensity photon beam in inverse Compton scattering (ICS) sources. The geometry and burst mode parameters of the FPC can be optimised to maximise the scattered photon flux. A novel optimisation method is presented, significantly improving processing speed and accuracy. The FPC’s dimensions, mirror requirements, and effective energy can be obtained from the electron beam parameters at the interaction point. A multi-objective optimization algorithm was used to derive the geometrical parameters of the FPC; this brought orders of magnitude increase in computation speed if compared to the nominal Monte Carlo-based approaches. The burst mode parameters of the FPC were obtained by maximizing the effective energy of the laser pulse in the FPC. The impact of optical losses and thermal lensing on the FPC parameters is addressed. Preliminary parameters of an ICS source implementing this novel optimisation are presented. The source could reach high-performance photon beams for high-energy applications.

Slides TU1C1 [1.776 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C1

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Received ※ 22 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU1C2

Evolution of the Inverse Compton Scattering X-ray Source of the ELSA Accelerator

50

A. Pires, R. Rosch, J. Touguet
CEA, Arpajon, France
N. Delerue
Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
V. Le Flanchec
CEA/DAM/DIF, Arpajon, France

The Inverse Compton Scattering (ICS) X-ray source of ELSA accelerator at CEA-DAM, presents an efficient approach for generating X-rays with a compact linac. The source consists of a 30 MeV, 15 ps rms, up to 3 nC electron beam; and a table-top Nd:YAG laser. X-rays are produced in the 10-80 keV range, higher X-ray energies achieved with frequency doubling of the laser. The yield is increased by a factor of 8 thanks to an optical mirror system developed at CEA, folding the laser beam path and accumulating successive laser pulses. We present a new version of the device, with improvement of mechanical constraints management, adjunction of motorized mirrors, and a new imaging system. A Chirped Pulse Amplification (CPA) system was also designed, enabling higher amplification levels without exceeding laser damage threshold. The uniqueness of this CPA system lies in its use of a short wavelength bandwidth, ±250 pm after Self-Phase Modulation (SPM) broadening, and a line density of 1850 lines/mm for the gratings of the compressor. The pulse is stretched with a chirped fiber Bragg grating (CFBG) before amplification in Nd:YAG amplifiers, and compressed by a double pass grating compressor.

Slides TU1C2 [7.085 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C2

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Received ※ 25 August 2023 — Revised ※ 25 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU1C3

A Compton Light Source Based on Counter Propagating Direct Laser Acceleration Channels

T. Meir, I. Cohen, L. Perelmutter, I. Pomerantz
Tel Aviv University, Tel-Aviv, Israel
A.V. Arefiev, K. Tangtartharakul
UCSD, La Jolla, California, USA
T. Cohen
Soreq NRC, Yavne, Israel

For the past two decades, intense lasers have supported new schemes for generating high-energy particle beams in university-scale laboratories. With the direct laser acceleration (DLA) method, the leading part of the laser pulse ionizes the target material and forms a positively charged ion plasma channel into which electrons are injected and accelerated. A striking feature of DLA is the extremely high conversion efficiency from laser energy to MeV electrons, with reported values as high as 23%, which makes this mechanism ideal for generating large numbers of photo-nuclear reactions. DLA is well understood and reproduced in numeric simulations. However, the electron energies obtained with the highest laser intensities available nowadays, fail to meet numerical predictions. In an experimental campaign, followed by a numerical investigation, we revealed that at these higher laser intensities, the leading edge of the laser pulse may deplete the target material of its ionization electrons prematurely. We demonstrated that for efficient DLA to prevail, a target material of sufficiently high atomic number is required to maintain the injection of ionization electrons at the peak intensity of the pulse when the DLA channel is already formed. I will present a numerical study on employing this new understanding for realizing a high brightness Compton light source in two counter-propagating DLA channels. Our 3D particle-in-cell results indicate small cone-angle photon emission in the multi 10s of keV spectral range, with few-fs duration and micron-scale source size.

Slides TU1C3 [6.684 MB]

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TU1C4

The CXFEL Project at Arizona State University

54

W.S. Graves
ASU, Tempe, USA

Funding: This work supported by National Science Foundation awards 2153503, 1935994, and 1632780.
The CXFEL Project encompasses the Compact X-ray Light Source (CXLS) that is now commissioning in the hard x-ray energy range 4-20 keV, and the Compact X-ray Free-Electron Laser (CXFEL) designed to lase in the soft x-ray range 300 ¿ 2500 eV. CXFEL has recently completed a 3-year design phase and just received NSF funding for construction over the next 5 years. These instruments are housed in separate purpose-built laboratories and rely on inverse Compton scattering of bright electron beams on powerful lasers to produce femtosecond pulses of x-rays from very compact linacs approximately 1 m in length. Both instruments use recently developed X-band distributed-coupling, room-temperature, standing-wave linacs and photoinjectors operating at 1 kHz repetition rates and 9300 MHz RF frequency. They rely on recently developed Yb-based lasers operating at high peak and average power to produce fs pulses of 1030 nm light at 1 kHz repetition rate with pulse energy up to 400 mJ. We present the current commissioning performance and status of CXLS. We also review the design and initial construction activities of the large collaborative effort to develop the fully coherent CXFEL.

Slides TU1C4 [7.974 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU1C4

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Received ※ 30 August 2023 — Revised ※ 31 August 2023 — Accepted ※ 01 September 2023 — Issued ※ 02 December 2023

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TU4P31

A Recursive Model for Laser-Electron-Radiation Interaction in Insertion Section of SSMB Storage Ring Based on Transverse-Longitudinal Coupling Scheme

147

C.-Y. Tsai
HUST, Wuhan, People’s Republic of China
X.J. Deng
TUB, Beijing, People’s Republic of China

Funding: This work is supported by the Fundamental Research Funds for the Central Universities (HUST) under Project No. 2021GCRC006 and National Natural Science Foundation of China under project No. 12275094.
Recently a mechanism of the steady-state microbunching (SSMB) in a storage ring has been proposed and investigated. The SSMB aims to maintain the same excellent high repetition rate, close to continuous-wave operation, as the storage ring. Moreover, replacing the conventional RF cavity with a laser modulator for longitudinal focusing, the individual electron bunches can be microbunched in a steady state. The microbunched electron bunch train, with individual bunch length comparable to or shorter than the radiation wavelength, can not only produce coherent powerful synchrotron radiations but may also be subject to FEL-like collective instabilities. Our previous analysis was based on the wake-impedance model*. In this paper, we have developed a recursive model for the laser modulator in the SSMB storage ring. In particular, the transverse-longitudinal coupling scheme is assumed**. Equipped with the above matrix formalism, we can construct a recursive model to account for turn-by-turn evolution, including single-particle and second moments. It is possible to obtain a simplified analytical expression to identify the stability regime or tolerance range for non-perfect cancellation.
*C.-Y. Tsai, PRAB 25, 064401 (2022). C.-Y. Tsai, NIMA 1042 (2022) 167454.
**X.J. Deng et al., NIMA 1019 (2021) 165859.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P31

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Received ※ 23 August 2023 — Revised ※ 24 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P33

An Inverse-Compton Scattering Simulation Module for RF-Track

151

A. Latina, V. Mușat
CERN, Meyrin, Switzerland

A simulation module implementing Inverse-Compton scattering (ICS) was added to the tracking code RF-Track. The module consists of a special beamline element that simulates the interaction between the tracked beam and a laser, making RF-Track capable of simulating a complete ICS source in one go, from the electron source to the photons. The description of the laser allows the user to thoroughly quality the laser in terms of wavelength, pulse energy, pulse length, incoming direction, M2 parameter, aspect ratio, polarisation and whether the laser profile should be Gaussian or uniform. Furthermore, as the code implements fully generic expressions, the scattering between photons and different particles than electrons can be simulated. A benchmark against CAIN showed excellent agreement and that RF-Track outperforms CAIN in terms of computational speed by orders of magnitude.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P33

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Received ※ 22 August 2023 — Revised ※ 28 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TU4P34

Recent Developments of the cSTART Project

155

M. Schwarz, A. Bernhard, E. Bründermann, D. El Khechen, B. Härer, A. Malygin, A.-S. Müller, M.J. Nasse, G. Niehues, A.I. Papash, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski, C. Widmann
KIT, Karlsruhe, Germany

The combination of a compact storage ring and a laser-plasma accelerator (LPA) can serve as the basis for future compact light sources. One challenge is the large momentum spread (~ 2%) of the electron beams delivered by the LPA. To overcome this challenge, a very large acceptance compact storage ring (VLA-cSR) was designed as part of the compact STorage ring for Accelerator Research and Technology (cSTART) project. The project will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a source of ultra-short bunches, will serve as an injector for the VLA-cSR to benchmark and emulate LPA-like beams. In a second stage, a laser-plasma accelerator will be used as an injector, which is being developed as part of the ATHENA project in collaboration with DESY and the Helmholtz Institute Jena (HIJ). The small facility footprint, the large-momentum spread bunches with charges from 1 pC to 1 nC and lengths from few fs to few ps pose challenges for the lattice design, RF system and beam diagnostics. This contribution summarizes the latest results on these challenges.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TU4P34

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Received ※ 21 August 2023 — Revised ※ 22 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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WE2C1

Population Inversion X-ray Laser Oscillator at LCLS and LCLS-II

A. Halavanau, A. Aquila, U. Bergmann, C. Pellegrini
SLAC, Menlo Park, California, USA
A.I. Benediktovitch
DESY, Hamburg, Germany
N. Majernik
UCLA, Los Angeles, California, USA
N. Rohringer
Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
N.B. Welke
UW-Madison/PD, Madison, Wisconsin, USA

The advancement of X-ray Free Electron Lasers (XFELs) has created revolutionary new research opportunities, owing to their high peak and average power, transverse coherence, and short pulse duration. Despite their remarkable capabilities, XFEL pulses lack longitudinal coherence and are not transform-limited, which limits their utilization, e.g. in quantum optics and precision interferometry. We explore the development of coherent, transform-limited pulses through alternative strategies, namely, X-ray lasers based on population inversion. We propose a novel approach relying on the principle of stimulated emission in the hard X-ray regime, using the XFEL as a pump. We will specifically discuss the case of the X-ray Laser Oscillator (XLO) at the LCLS copper linac and the planed LCLS-II-HE. Our recent work has shown the feasibility and performance characteristics of these systems, which can operate over a broad wavelength range from 5 to 12 keV. Future applications at LCLS-II-HE might allow for transform-limited XLO pulses with repetition rates up to tens of kHz. We show that XLO is experimentally feasible and discuss its projected performance and photon pulse properties operating at the Copper K-alpha1 line. Finally, we discuss possible first experiments with XLO.

Slides WE2C1 [2.756 MB]

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WE2C2

Harmonic Generation from keV-electron-excited Nano-grating

Y.-C. Huang
NTHU, Hsinchu, Taiwan

Funding: MOST 111-2221-E-007-001, Taiwan
There has been a recent interest in using free electrons to interact with photonic structures and generate light. The envisaged dielectric accelerator on a chip is a low-current electron source driven by a laser. The generated electron beam contains a few electrons in each optical cycle repeating at the driver laser frequency. We perform a feasibility study in this paper on the harmonic generation of a periodic array of single electrons with keV energy atop a dielectric grating waveguide. The device is a 31 um long silicon grating on top of a glass substrate, having a 400 nm thickness and 310-nm period. The structure is designed to have a Bragg resonance at 1.5 um in wavelength or 0.2 PHz in frequency for the radiation mode. We use the simulation code CST to study the radiation from a periodic array of 25 electrons. The electrons have 50 keV energy, injected one by one at 0.1 PHz at 100 nm above the grating. The transit time of the 50 keV electrons over the 31 um long silicon grating is 0.25 ps. Cherenkov radiation is guided in the silicon waveguide layer. Smith-Purcell (SP) radiation is generated in the vacuum region above the grating. We show in simulation a ring-down of the generated coherent radiations from both ends of the grating waveguide, indicating that a grating waveguide is a good Bragg resonator. The field pattern in the waveguide region satisfies the Bragg condition, i.e. structure periodicity = half of the longitudinal wavelength. The Fourier transform of the generated radiation wave has a narrow radiation spectrum at 0.2 PHz. A discrete spectrum of SP radiation mediated by the waveguide modes is also observed from simulation in the vacuum space above the grating waveguide. This study shows the feasibility of generating harmonic radiation from a nano-photonic structure driven by keV periodic electrons.

Slides WE2C2 [3.982 MB]

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TH2C1

The COXINEL Seeded Free Electron Laser Driven by the Laser Plasma Accelerator at HZDR

232

M.-E. Couprie, T. André, A. Berlioux, P. Berteaud, F. Blache, F. Bouvet, F. Briquez, Y. Dietrich, J.P. Duval, M. El Ajjouri, C. Herbeaux, N. Hubert, C.A. Kitégi, M. Labat, S. Lê, B. Leluan, A. Loulergue, F. Marteau, M.-H. Nguyen, D. Oumbarek Espinos, D. Pereira, J.P. Ricaud, P. Rommeluère, M. Sebdaoui, K. Tavakoli, M. Valléau, M.V. Vandenberghe, J. Vétéran, C. de Oliveira
SOLEIL, Gif-sur-Yvette, France
I.A. Andriyash, J. Gautier, J.-P. Goddet, O.S. Kononenko, G. Lambert, J.P. Rousseau, A. Tafzi, C. Thaury
LOA, Palaiseau, France
S. Bock, Y.Y. Chang, A.D. Debus, C. Eisenmann, R. Gebhardt, A. Ghaith, S. Grams, U. Helbig, A. Irman, M. Kuntzsch, R.G. Pausch, T. Püschel, S. Schöbel, U. Schramm, K. Steiniger, P. Ufer
HZDR, Dresden, Germany
M. LaBerge
The University of Texas at Austin, Austin, Texas, USA
V. Malka
Weizmann Institute of Science, Physics, Rehovot, Israel
E. Roussel
PhLAM/CERLA, Villeneuve d’Ascq, France

Laser Plasma Accelerators know a tremendous development these recent years. Being able to reach up to ~100 GV/m, they open new perspectives for compact accelerators. Their performance can be qualified by a Free Electron Laser Application. We report here on the COXINEL seeded Free Electron Laser in the UV using the using high-quality electron beam generated by the 150 TW DRACO laser. The COXINEL line developed at Synchrotron SOLEIL (France) is first introduced. First electron beam transport and undulator radiation observation using electrons from the Laser Plasma Accelerator developed at Laboratoire d’Optique Appliquée (France) are described. Then, we present the first COXINEL results driven by the DRACO laser high performance plasma accelerator after its move to Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Germany): proper electron beam transport, undulator seed and undulator radiation temporal, spectral and spatial overlaps, allowing the seeded Free Electron Laser to be observed in the UV. Good agreement is found between measurements and simulations.

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH2C1

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Received ※ 22 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 30 August 2023 — Issued ※ 02 December 2023

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TH2C2

Development of Laser-Driven Plasma Accelerator Undulator Radiation Source at ELI-Beamlines

237

A.Y. Molodozhentsev
Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic
J.T. Green, P. Zimmermann
ELI-BEAMS, Prague, Czech Republic
A. Jancarek, S.M. Maity, A. Mondal, S.N. Niekrasz, E. Vishnyakov
ELI ERIC, Dolni Brezany, Czech Republic

Over the last decade, the mechanism of the laser-plasma acceleration of electrons was studied intensively by many experimental teams aiming to achieve high-energy, high-quality electron beams required to generate high-brilliance incoherent and, as the next step, coherent undulator photon radiation for wide-range applications. The laser-driven plasma accelerator based compact undulator radiation source is currently under commissioning at ELI-Beamlines (Institute of Physics CAS, Czech Republic) in the frame of the LUIS project, which aims to deliver stable and reliable incoherent photon beam with a wavelength around 5 nm to an user-station. As the result of this project, the electron beam parameters should be improved to generate the coherent photon radiation reaching the saturation of the photon pulse energy in a single-unit dedicated undulator (LPA-based FEL). An overview of the current status of the LUIS project will be presented, including the high-power high-repetition rate laser, acceleration of the electron beam in the plasma channel, the electron and photon beam-lines with relevant diagnostics. Challenges and future development beyond the LUIS project also being discussed.

Slides TH2C2 [3.474 MB]

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reference for this paper ※ doi:10.18429/JACoW-FLS2023-TH2C2

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Received ※ 23 August 2023 — Revised ※ 29 August 2023 — Accepted ※ 31 August 2023 — Issued ※ 02 December 2023

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TH2C3

A Novel X-ray Free-electron Laser Scheme Based on Cascaded Laser Wakefield Accelerators

H.Y. Xiao, J.F. Hua, F. Li, W. Lu
TUB, Beijing, People’s Republic of China

Laser wakefield accelerators (LWFA) present great potential to drive a free-electron laser (FEL) in a compact footprint because of the extremely high accelerating gradient. However, there are still many obstacles to overcome before the LWFA-driven FEL device can truly achieve exponential amplification and saturated output. These problems include how to resolve the phase slippage effect caused by the fs-level length of LWFA beams, and how to stably generate high-quality beams and preserve the quality during the transport. In this presentation, a novel scheme of X-ray FEL based on cascaded LWFAs is proposed aiming at addressing the above issues. High-quality electron beams with stable central energy and relatively long beam length can be generated using staged LWFAs. With a dedicated beamline design, the longitudinal phase space, beam length and inter-stage coupling are optimized, and start-to-end simulations show that such beams can drive the XFEL to saturation. In addition, the proposed scheme also possesses the capability to adjust FEL radiation bandwidth through precise longitudinal phase space steering. Our scheme provides a highly viable new route to realize LWFA-driven compact XFEL devices.

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FR1M3

Summary Report of Working Group C: Compact Light Sources

Y.-C. Huang
NTHU, Hsinchu, Taiwan
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

The paper highlights the key points arising from four insightful and instructive working group sessions.

Slides FR1M3 [8.910 MB]

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